Chapter 16: Viruses Flashcards
Retrovirus
Contain an enzyme called reverse transcriptase.
Viroids
Naked circular RNA molecule that infects plants.
Prion
Misfolded form of protein, no genome, only affects animals.
Cause of Alzheimer’s & Parkinson’s.
How Viruses Enter Cells
Attach to specific receptor.
Injects genetic material or entire virus can enter eukaryotic cell.
Once inside, nucleic acids in virus take over cell & cause it to make more viral particles.
How Viruses Exit Cells
Causes cell to rupture (lysis).
Can insert small amount of DNA into host cell’s DNA. Cell divides with new copy of viral DNA.
Can exit via exocytosis.
3 Processes of Emerging Viruses
Mutation.
Contact between Species.
Spread from isolated populations.
Emerging Virus
Appears suddenly or is new to medical science.
3/4 new viral diseases arise from existing ones.
SARS
Severe Acute Respiratory Syndrome
How We Grow & Study Viruses
Cannot be grown in standard microbiological media.
Make tissue culture in petri dish, acceptable to virus.
Replicated in lab with polymerase chain reaction.
Most Common Virus
Rhinovirus
How Viruses Replicate
Viral DNA > Transcription > mRNA > translation > new viruses.
Virus Shapes
Rod- shaped.
Round with spikes.
Icosahedral (20 sides).
Icosahedral with rod body & tail fibres (called bacteriophages).
